【C++编程】boost::variant

boost::variant

#include <boost/variant.hpp> 
#include <string> 
#include <iostream> 

int main() 
{ 
  boost::variant<double, char, std::string> v; 
  v = 3.14; 
  std::cout << v << std::endl; 
  v = 'A'; 
  std::cout << v << std::endl; 
  v = "Hello, world!"; 
  std::cout << v << std::endl; 
} 

1. 实例

#include <boost/variant.hpp>
#include <boost/any.hpp>
#include <vector>
#include <string>
#include <iostream>

std::vector<boost::any> vector;

struct output : public boost::static_visitor<>
{
  void operator()(double &d) const
  {
    vector.push_back(d);
    std::cout << "double: " << d << std::endl;
  }

  void operator()(char &c) const
  {
    vector.push_back(c);
   std::cout << "char: " << c << std::endl;
  }

  void operator()(std::string &s) const
  {
    vector.push_back(s);
    std::cout << "string: " << s << std::endl;
  }
};

int main()
{
  boost::variant<double, char, std::string> v;
  v = 3.14;
  boost::apply_visitor(output(), v);
  v = 'A';
  boost::apply_visitor(output(), v);
  v = "Hello, world!";
  boost::apply_visitor(output(), v);
}

输出：

[root@node01 demo]# g++  -std=c++11 -lboost_system -lpthread -I/usr/local/include/boost -L/usr/local/lib  demo.cc  -o demo
[root@node01 demo]# ./demo 
double: 3.14
char: A
string: Hello, world!

参考资料

1. boost数据结构